docs: def differential_pressure_meter_beta(D, D2, meter_type):
      r'''Calculates the beta ratio of a differential pressure meter.
          
      Parameters
      ----------
      D : float
          Upstream internal pipe diameter, [m]
      D2 : float
          Diameter of orifice, or venturi meter orifice, or flow tube orifice,
          or cone meter end diameter, or wedge meter fluid flow height, [m]
      meter_type : str
          One of ('ISO 5167 orifice', 'long radius nozzle', 'ISA 1932 nozzle', 
          'venuri nozzle', 'as cast convergent venturi tube', 
          'machined convergent venturi tube', 
          'rough welded convergent venturi tube', 'cone meter',
          'wedge meter'), [-]
  
      Returns
      -------
      beta : float
          Differential pressure meter diameter ratio, [-]
  
      Notes
      -----
      
      Examples
      --------
      >>> differential_pressure_meter_beta(D=0.2575, D2=0.184, 
      ... meter_type='cone meter')
      0.6995709873957624
      '''
      if meter_type in beta_simple_meters:
          beta = D2/D      
      elif meter_type == CONE_METER:
          beta = diameter_ratio_cone_meter(D=D, Dc=D2)
      elif meter_type == WEDGE_METER:
          beta = diameter_ratio_wedge_meter(D=D, H=D2)
      return beta